EP0714070B1

EP0714070B1 - Bar code label

Info

Publication number: EP0714070B1
Application number: EP96100836A
Authority: EP
Inventors: Hiroo c/o NEC Corporation Wakumi; Hiroshi c/o Nippon Elec. Ind. Co. Ltd. Ajiki
Original assignee: NEC Corp; Nippon Electric Industry Co Ltd
Current assignee: NEC Corp; Nippon Electric Industry Co Ltd
Priority date: 1990-01-31
Filing date: 1991-01-28
Publication date: 1998-07-08
Anticipated expiration: 2011-01-28
Also published as: EP0714072A2; EP0714071B1; EP0714071A2; EP0714071A3; US5268566A; EP0714070A3; DE69129762D1; DE69127912D1; EP0714070A2; DE69129762T2; DE69129763D1; EP0714072A3; EP0440124B1; US5235169A; EP0440124A1; DE69129763T2; DE69127912T2

Description

The present invention relates to a bar code label in which information on each of various commodities, outdoor installations or individuals are recorded as engraved in the form of characters and bar codes.

The bar code label is well known and widely used as attached on the surface of a box or package in which a commodity or delivery is packed. The bar code label carries a variety of information, as coded in the form of bars different in width from one another, on such commodity. The information are used for a higher efficiency and less labor in sales calculation, inventory control or assortment.

Generally, such bar code is black bars printed on the white surface of a bar code label.

If the label surface is stained with an oil or dirt or if the blackness of the coded bars fades, the information recorded in the bar code label cannot possibly be read positively and accurately. Particularly, there is a problem in reading the bar code label outdoors.

Recently, a magnetic bar code reading system has been proposed which can be used in any environment. In this system, engraved recesses (characters and bar codes) 202, 202 ' , 203 , · · · are made, as shown in Fig. 1, on a bar code label 201 made of a metal such as iron and the recesses are magnetically detected by means of a ferromagnetic magnetic resistance device (will be referred to as "MR device" hereinafter) and a permanent magnet. More particularly, the head at the bottom of a main body 204 in which the MR device and permanent magnet are integrally incorporated is swept on the engraved bar code label 201 to read the recess pattern consisting of the

recesses

202, 202 ' , 203 , · · · . The principle of this bar code reading will be discussed below:

When the head is placed on the engraved bar code label 201, the engraved

recesses

202, 202' , 203 , · · · are magnetized by the DC magnetic formed by the permanent magnet. The magnetic field formed by these magnetized recesses causes the magnetic flux distribution over the recesses to change and this change of the magnetic flux distribution results in a resistance change of the MR device. The resistance change is passed to the signal processing circuit provided in the head of the main body 204 in which they are converted into a binary-coded signal (0 or 1) correspondingly to the code represented by the recess pattern. This binary-coded signal is supplied to the decoder for recognition of the bar code pattern.

The conventional head of the magnetic bar code reader operating on the above-mentioned principle has a tip of which the structure will be discussed below with reference to Fig. 2. Namely, for an electrical connection between an input wire of an MR device 206 made on a printed circuit board 205 through a well-known IC manufacturing process and an external lead wire 207 through which a current is supplied to detect a magnetic field change as a voltage, the circuit board 205 is connected to an electrode 209 by means of a bonding wire 208 and the external lead wire 207 is spot-joined to the electrode 209 by means of a solder joint 210. The electrode 209 and circuit board 205 are attached to an internal substrate 211. Further, the internal substrate 211 and electrode 209 are attached to a head frame 212 and sealed from below with a coating film 213. A permanent magnet 214 provided for exciting is attached to the internal substrate 211 and sealed with a coating film 215.

As the conventional sensor of the magnetic bar code reader operating on the above-mentioned principle, a generally square MR device is used as shown in Fig. 3. As seen, a magnetic resistance film 217 formed on a circuit board 216 made of, for example, a glass is provided in such a structure that it is folded back in parallel to the lateral side of the circuit board 216. For a high magnetic sensitivity, a plurality of such magnetic resistance films is provided as cascade-connected. Usually, the number of the magnetic resistance films thus provided is such that the whole resistance will be on the order several kiloohms. Furthermore, a current-supplying electrode 218 is provided on either end of the magnetic resistance film 217 in such a manner that an ohmic contact can be assured. For a higher yield of manufacture with a reduced IC area, these patterns are so set as to form together a generally square shape in many cases.

In a magnetic bar code reader. the above-mentioned MR device is inclined more than 30 deg. with respect to bar code recesses 219 and a permanent magnet 220 which applies a biasing magnetic field is provided on the MR device to make a head 221 which will be swept on recesses 223, engraved in the form of bar code in an iron sheet 222, in a direction perpendicular to the length of the engraved recesses 223, thereby reading the bar code.

A bar code label made of any other metal sheet than the iron sheet is so resistant against contamination or staining that even when the label surface is stained with a dirt or the like, it can be washed with water to remove such dirt. However, in case the label is made of an iron sheet, it will be rusty and thus corroded. Particularly, any iron-sheet bar code label is not suitably usable in a place where the atmosphere is very salty.

In the head having the structure shown in Fig. 2, since the bonding wire 208 is provided as bonded to the electrode 205 on the substrate (semiconductor substrate) of the MR device 206 by using an ultrasonic bonder or the like, a air gap d (about 0.3 mm) must be provided under these elements. This air gap causes the strength of the magnetic lines of force produced by the engraved recesses, that is to be detected by the MR device, to he extremely small. In other words, the MR device has only a low sensitivity to the magnetic lines of force formed by the bar code recesses. When the head is off the bar code label, the sensitivity of the MR device is found very low. For example, when about 0.1 mm is off the label surface in relation to a pattern of minimum recesses of 0.5 mm, the head can hardly read the code represented by the recess pattern.

In the bar code reader having a magnetic sensor of a structure shown in Fig. 3, since the magnetic resistance film 217 occupies so large inside the reader as extends fully across one engraved recess, so the changes of magnetic field in opposite directions at the right and left recess edges cancels the magnetic resistance change of the MR device. Thus, this reader cannot read any high resolution engraved bar code composed of narrow recesses. For example, a common MR device of 0.5 to 0.6 mm in length and width should preferably be inclined 45 deg. with respect to the length of the recesses to apply a biasing magnetic field longitudinally of the recesses in order to read the bar code with a high sensitivity. In this case, however, the width of the MR device will be about 0.7 mm to 0.85 mm and thus it is apparent that the MR device cannot read any engraved recess of 0.5 mm in minimum width. Also even if a bar code reading head is constructed with the MR device not inclined 45 deg. (the biasing magnetic field may be applied from a direction inclined 45 deg.) but directed longitudinally of the engraved recesses at the sacrifice of the sensitivity to some extent, any common magnetic sensor element having a large width, if fitted, in the head cannot read a high resolution (namely, narrow) bar code recess pattern.

JP-1 280 593, on which the preamble of claim 1 is based, discloses a bar code label having information recorded therein, the bar code label comprising: a base; and a recording area provided on the top surface of the base, the recording area being provided with recesses engraved each in a predetermined shape corresponding to information to be recorded.

JP-1 233 675 discloses a bar code label similar to that described in JP-1 280 593.

A first aspect of the present invention provides a bar code label having information recorded therein, the bar code label comprising: a base of a magnetic material; and a recording area provided on the upper surface of the base, the recording area being provided with recesses engraved each in a predetermined shape corresponding to information to be recorded; wherein the upper surface of the base is coated with a non-magnetic material;
characterised in that narrower recesses are engraved deeper than wider recesses.

A second aspect of the present invention provides a bar code label having information recorded therein, the bar code label comprising: a base of a magnetic material; and a recording area provided on the upper surface of the base, the recording area being provided with recesses engraved each in a predetermined shape corresponding to information to be recorded; and wherein the base of the bar code label is coated with a stainless material;
characterised in that narrower recesses are engraved deeper than wider recesses.

In a preferred embodiment the stainless material is a plastics material, lead, tin or nickel.

These and other objects and advantages of the present invention will be better understood from the following description made, by way of example, of the embodiments of the present invention with reference to the drawings:

Fig. 1 is a schematic illustration of the essential part of the bar code reader;

Fig. 2 is also a schematic illustration showing the construction of the head of the conventional bar code reader;

Fig. 3 schematically illustrates the construction of the conventional bar code reader having a MR device;

Fig. 4 is a perspective view of a bar code label;

Fig. 5 is a sectional view of a bar code label;

Fig. 6 is a sectional view of a bar code label according to the embodiment of the present invention.

Fig. 4 shows a bar code label, this engraved bar code label comprising a base 1 having formed a protective film 2 on the outer surface thereof.

The base 1 is a square sheet made of a material such as iron or the like, the sheet having the top and bottom surfaces thereof machined like a mirror surface to minimize the surface irregularity. The base 1 has formed as engraved on the top surface thereof a record area 3 carrying, for identification, a variety of information on, for example, the name of a unit or force to which a solder belongs or the proprietor, serial number or the line of an outdoor installation such as construction machine, vehicle, gas cylinder, machine part, steel tower or the like. The record area 3 consists of recesses different in width from each other correspondingly to various information. In this first embodiment, the recesses are formed by etching or punching.

The protective film 2 is provided to protect the record area 3 for a long term being eroded, and it is selected from among plastic, nickel, lead(Pb) or tin (Sn). The stainless material such as plastic, nickel or the like is applied as a thin film on the entire surface of the base 1. The lead or tin is applied as plated on the entire surface of the base 1.

Thus, the protective film 2 is applied on the entire surface of the base 1. Namely, it can be easily manufactured with less manufacuturing costs.

Fig. 5 shows another bar code label. This engraved bar code label comprises a film-shaped base 4 made of a ferromagnetic material such as iron (Fe), cobalt(Co), nickel(Ni) or the like and on which a record area 5 is provided which concists of recesses different in width from each other and which are engraved with a predetermined spacing from one to another recess, and a nonmagnetic film 6 so molded in the record area 5 or the base 4 as to completely bury the recesses.

Similar to the base having been discussed above, the base 4 has the top and bottom surfaces thereof machined with a high precision like a mirror face to prevent any read error form taking place.

The record area 5 has engraved in the top surface of the base 4 recesses each having a predetermined width corresponding to an information to be recorded, spaced a predetermined distance between adjoining one and engraved to a predetermined depth d. When this record area 5 is applied with a magnetic field from outside by the magnet or the like, the magnetic lines of force are concentrated laterally of the recesses, resulting in a distortion of the distribution of the magnetic lines of force. By detecting the components of the distribution in the direction of the distribution width, signals corresponding to the edges of the recesses, and further by decoding the signals, the original record pattern can be recognized and reproduced.

The nonmagnetic film 6 is a mold of a nonmagnetic material such as plastic or the like to a predetermined thickness to the record area 5.

The embodiment of the present invention will be discussed below:

Fig. 6 shows the engraved bar code label, in which the depth d₁ of a recess 7 of smaller width W₁ is larger than the depth d₂ of a one 7 of larger width W₂, namely, d₁ > d₂.

Because the depth d₂ is smaller than the depth d₁, it is possible to prevent the magnetic field near the wide recess from being destorted largely, which leads to less distortion of the magnetic field on the adjoining narrow recess.

Therefore, according to this third embodiment, the recess width is changed correspondingly to the recess width; thus, the output waveform corresponding to the recess 7 is less distorted during the information reading and thus a high information density, namely. high resolution bar code label can be read accurately.

As having been discussed in the foregoing, the bar code label according to the present invention has recesses engraved in a record area on the bar code label. Even with any staining, sunlight or the like, the record area cannot be lost. Therefore, information can be positively recorded on the bar code label, praticularly in outdoor use for a long term.

The magnetic engraved bar code label according to the present invention permits to record an information on the magnetic material with a width and spacing corresponding to the information based on the fact that when the record area made of a magnetic material is applied with an external magnetic field from a ferromagnetic material such as a magnet or the like, the distribution of magnetic lines of line produced by the respective recesses in the record area is changed at the recess edges.

The engraved bar code labels according to the present invention are made of a magnetic material (metal) coated with a resin or the like. So even if stained or somewhat impaired, the label can still be used. Namely, it can be suitably used in an environment such as outdoor, factory or the like where the label is likely to be stained.

Claims

A bar code label having information recorded therein, the bar code label comprising: a base (1) of a magnetic material; and a recording area (3) provided on the upper surface of the base, the recording area (3) being provided with recesses engraved each in a predetermined shape corresponding to information to be recorded; wherein the upper surface of the base (1) is coated with a non-magnetic material;
characterised in that narrower recesses (7) are engraved deeper than wider recesses.
A bar code label having information recorded therein, the bar code label comprising: a base (1) of a magnetic material; and a recording area (3) provided on the upper surface of the base, the recording area (3) being provided with recesses engraved each in a predetermined shape corresponding to information to be recorded; and wherein the base of the bar code label is coated with a stainless material (2);
characterised in that narrower recesses (7) are engraved deeper than wider recesses.
A bar code label as claimed in claim 2 wherein the stainless material is a plastics material, lead, tin or nickel.